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  3. Since there is such an abundance of food in the sea, it is understandable that some of the efficient, highly adaptable, warm-blo

Since there is such an abundance of food in the sea, it is understandable that some of the efficient, highly adaptable, warm-blo

admin2013-02-16  92
问题     Since there is such an abundance of food in the sea, it is understandable that some of the efficient, highly adaptable, warm-blooded mammals that evolved on land should have returned to the sea. Those that did do that have flourished. Within about 50 million years—no time at all, geologically speaking —one of the four kinds of mammals that has returned to a marine environment has developed into the largest of all animal forms, the whale. A second kind, the seal, has produced what is probably the greatest population of large carnivorous mammals on Earth. This suggests that these "top dogs" of the ocean are prospering and multiplying. However, such has not been the case, at least not for the last 150 years. Trouble has closed in on these mammals in the form of equally warm-blooded and even more efficient and adaptable predators, humans. At sea, as on land, humans have now positioned themselves on top of the whole great pyramid of life, and they have caused serious problems for the mammals of the sea.
    There is a simple reason for this. Marine mammals have the misfortune to be swimming aggregates of commodities that humans want: fur, oil, and meat. Even so, they might not be so vulnerable to human depredation if they did not, like humans, reproduce so slowly. Every year humans take more than 50 million tons of fish from the oceans without critically depleting the population of any species. But the slow-breeding mammals of the sea have been all but wiped out by humans seeking to satisfy their wants and whims.
What advantage did some land mammals gain by returning to the sea?
选项 A、Fewer predators exist in the sea.
B、More space is available in the sea.
C、There is a greater supply of food in the sea.
D、The climate is more hospitable in the sea.
答案C
解析 根据文章第一段第一句“Since there is such an abundance of food in the sea，it is understandable that some of the efficient，highly adaptable，warm-blooded mammals that evolved on land should have returned to thesea．”可知，既然海洋中的食物如此丰富，一些在陆地进化生活的高效率、适应性强的热血动物其实就应该返回到海洋去。所以，陆地哺乳动物如果返回到海洋的话，可以得到更多的食物。据此判断，答案是C。
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